Moving small aircraft on the ground is often necessary when the aircraft is serviced or taken to a hanger or brought out. In the past, the motor has been started and the aircraft's own power has moved it from one place to another. This, of course, presents a potential danger from the rotating propeller. It also produces unnecessary wear and stress on the motor when it is operated for just a short while.
As an alternative, aircraft tugs have been employed, much like the large tugs that move commercial jet aircraft and the like. However, this requires a significant investment in equipment costs for operating the tug. It also requires having someone available to operate the device and/or train small aircraft owners to use the machine.
It would be of great advantage if a simple, efficient device could be developed that would permit owners to move their own planes without worrying about safety concerns from the motor of the plane.
One such device has been proposed. Olson U.S. Pat. No. 4,915,185 discloses a portable aircraft moving device using a portable electric drill. The drill output shaft is linked to a worm gear to mount temporarily to the front wheel of the airplane above the airplane wheel. While the drawings of this patent are clearly not intended to be to scale, the size of the airplane and the operator distort the difficulties of moving aircraft that may weigh several thousand pounds. Olson requires a drive wheel in the device to engage the aircraft front wheel and use that wheel to push or pull the aircraft. One additional drawback of Olson is that it places frictional stress on the nose wheel. It is not adaptable to all aircraft, requiring a specific axle adapter for each make or model.
Other patents have also found use for portable electric drills. Hawgood U.S. Pat. No. 4,156,315 discloses a dolly for maneuvering trailers, again using a worm gear.
Perkins U.S. Pat. No. 4,280,578 teaches the use of an electric drill for a walker for the disabled, a far less substantial weight and effort than aircraft. Perkins also uses a worm gear arrangement.
Finally, Hurt U.S. Pat. No. 3,713,501 employs an electric drill to alternatively move a belt to elevate the hand truck up or down stairs or move the wheel axle of the hand truck on flat ground. None of these other devices suggest a simple, effective method for moving small aircraft without frictional engagement with the nose wheel of the aircraft, and without having separate fittings for each make or model of the plane being moved.
In my earlier continuation-in-part application, a solution to the problems of the prior are is described and claimed. In my newer copending application, the design was modified to make the device steerable, producing substantial advantages including the ability to move much heavier aircraft because of the steerable features. In this application, the tug design is improved to make it transportable without major assembly or the use of tool. It also has a much higher capacity and has an improved steering option.
Other advantages will appear hereinafter.